Experience with VQM in Italy

Transcription

1 Experience with VQM in Italy Ferruccio Villa AEEG Head of Electricity Quality of Supply Michele de Nigris ERSE Director - Dpt T&D Technologies michele.denigris@erse-web.it EURELECTRIC - CEER joint Workshop on Voltage Quality Monitoring Brussels, 18 th November 2009 Autorità per l'energia elettrica e il gas 1 CHRONOLOGY AEEG promotes monitoring campaign on MV networks ERSE carries out the monitoring activity 400 points HV/MV SS and 200 MV delivery points Data correlation and lessons learned Proposal for a new VQM phase? April 2005 February 2006 October 2009 Early 2010 Second half 2010 Continuous deployment of smart meters fit for recording slow voltage variations according EN Autorità per l'energia elettrica e il gas 2

2 2005: OBJECTIVES BEHIND THE MONITORING CAMPAIGN Knowledge of the performances of the MV networks and publication of them Making aware customers about tools that quality regulation makes available to them (quality contracts, individual measurements) Correlation of measured data to the structure of the network, power of HV/MV transformers, short circuit power at delivery points, load characteristics, presence of disturbing loads, presence of distributed generation Assess responsibilities, as far as possible Assess the possibility of introducing measurement obligations for DNOs and then a financial regulation of some PQ indicators Make use of the results of the monitoring campaign in order to confirm or revise limit values of PQ indicators so that they can reflect the characteristics of the Italian electrical system Autorità per l'energia elettrica e il gas 3 PUBLICATION OF VQ DATA VQ data are available on-line on: Some data (in particular regarding dips) were published in the 4 th Ceer Benchmarking Report on Quality of Electricity Supply Italy, Year 2007, all types of MV networks, MV bus-bars of HV/MV substations Yellow cells: equipment immunity class 2 Yellow+ Green: equipment immunity class 3 Red line: compatibility curve Autorità per l'energia elettrica e il gas 4

3 MONITORING UNITS INSTALLED 400 monitoring units (they monitor about 10% of the MV bus-bars of the MV distribution network). The sample is representative of the network characteristics in terms of: number of HV/MV substations in each region length of the MV lines type of MV lines: cable, overhead, mixed neutral compensation or isolated neutral number of MV customers density of LV customers 73 owned by as many MV customers who decided to voluntarily (with the promotion of the Authority) participate to the monitoring campaign 124 owned by Distribution Network Operators This sample of units is not statistically representative of the monitored MV network Autorità per l'energia elettrica e il gas 5 ROUGH RESULTS VOLTAGE DIPS Buchi di tensione classificati VERI dal filtro 01GIU-18LUG RESIDUAL VOLTAGE (%) Tensione residua(%) NUMBER OF EVENTS Durata(ms) VOLTAGE DIP DURATION (ms) Autorità per l'energia elettrica e il gas 6

4 WHAT DID WE LEARN IN 3 YEARS OPERATION? MEASURING SYSTEM SYSTEM MANAGEMENT Voltage sensors: in HV/MV substation PH-GR sensors (VTs) is most common Specific connection and saturation of VTs may generate false positive events mainly in case of 1-ph-gr faults especially on Isolated neutral network portions. (~30% events) Need of filtering algorithm to get rid of false positives (or change of sensors..) Instrument cost is marginal with respect to implementing M&O costs Customized solutions are necessary Continuous maintenance and updating Autorità per l'energia elettrica e il gas 7 WHAT DID WE LEARN IN 3 YEARS OPERATION? DATA ANALYSIS HV/MV station observation point is suitable to monitor what happens downstream (for dips) Monitoring campaign shall cover several years as there is a wide variability of data on the single site in consecutive years The single measurement point dip-performance shows high variability year after year Nationwide, the dip-performance shows stable trends (variations 2-3% over the years) About 30% of the events are transferred from HV networks Multiple linear regression models are necessary to analyze the data and derive learning Autorità per l'energia elettrica e il gas 8

5 CAN I ESTIMATE THE VOLTAGE-DIP PERFORMANCE FOR NEXT YEAR IN A SPECIFIC POINT? SUPPOSE I WANT TO ESTIMATE THE VALUE OF THE VOLTAGE DIP FOR 2008 BASED ON THE AVERAGE VALUE OF ON THE SAME MEASURING POINT DATA 2006 FOR POINT a DATA 2008 FOR POINT a DATA 2007 FOR POINT a ESTIMATION FOR 2008 EVALUATION OF THE ERROR Autorità per l'energia elettrica e il gas 9 CAN I ESTIMATE THE VOLTAGE-DIP PERFORMANCE FOR NEXT YEAR IN A SPECIFIC POINT? p.u. estimation error N3(a) Error that would have been done in estimating the expected number of dips in 2008 starting from the actual number of dips of point = 1 measuring location Autorità per l'energia elettrica e il gas 10

6 LEARNING FROM THE MULTIPLE LINEAR REGRESSION MLR Allows to analyze data dividing variables between influencing/not relevant and to quantify the contribution of each variable independently of all others. Factors having high influence: Geographical aspects Length of overhead lines Neutral operation (isolated vs. compensated) Factors having little influence Length of underground cables System voltage Factors needing more precise data Lightning Autorità per l'energia elettrica e il gas 11 GEOGRAPHICAL ASPECTS DIFFERENCES IN DIP PERFORMANCES ARE INDEPENDENT FROM ALL OTHER PARAMETERS -> LINKED WITH OTHER FACTORS (ASSET MANAGEMENT?) INTERESTING FOR THE DISTRIBUTOR TO INVESTIGATE POTENTIAL ASPECTS NOT LINKED WITH NETWORK STRUCTURE AND FIND APPROPRIATE SOLUTIONS Autorità per l'energia elettrica e il gas 12

7 LIGHTNING N2(a) THERE IS APPARENTLY A VERY GOOD CORRELATION BETWEEN LIGHTNING ACTIVITY TO GROUND Ng AND THE DIP PERFORMANCES N2(a) MLR REVEALS THAT: THE REAL DATA IS STRONGLY BIASED BY THE GEOGRAPHICAL ASPECTS Ng DOES NOT MODIFY THE DIFFERENCES BETWEEN THE AREAS La IS SUFFICIENT TO CONSIDER LIGHTNING AND ALL OTHER EVENTS CAUSING LINE FAULTS Ng Autorità per l'energia elettrica e il gas 13 RESULTS OF THE MONITORING CAMPAIGN VS. OBJECTIVES Knowledge of the performances of the MV networks and publication of them Making aware customers about tools that quality regulation makes available to them (quality contracts, individual measurements) Correlation of measured data to the structure of the network, power of HV/MV transformers, short circuit power at delivery points, load characteristics, presence of disturbing loads, presence of distributed generation Assess responsibilities, as far as possible Assess the possibility of introducing measurement obligations for DNOs and then a financial regulation of some PQ indicators Make use of the results of the monitoring campaign in order to confirm or revise limit values of PQ indicators so that they can reflect the characteristics of the Italian electrical system EN New consultation phase in 2010 Autorità per l'energia elettrica e il gas 14

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